tsarnaev. >> reporter: as he was cornered, dzhokhar tsarnaev, police say, engaged them with gunfire. it it went on for several minutes and police lobbed in flash-bangs to stun him. in the end, authorities showed their determination to capture the suspect alive. listen to officers negotiating with him as he's holed up inside a boat in a backyard in watertown. >> come out with your hands up. >> reporter: we snaked through allies to get to within a couple hundred yards of the poet. during negotiations there was a word of reassurance and an appeal to someone they knew was in pain. >> we know you're bleeding and we know you're tired. >> reporter: as we shot this excleesive video police rushed us saying we were in the cross fire zone. it was just minutes later that police captured tsarnaev. he had lost blood, was weakened. these pictures show thermal imaging from a helicopter of the suspect as he hid in the boat. the entire neighborhood had been on lockdown. residents terrified as law enforcement went door to door. after the standoff we spoke to neighbors. here on cyprus street, this is on